Improved pin-drill



UNITED STATES PATENT OEEIoE.

THOMAs rnossEe, or NEW YORK, N. Y.

IMPROVED PIN-DRILL.

Specification forming part of Letters Patent No. 89,502, dated April 27,1869.

To all 'whom it may concern:

Be it known that I, THOMAS Pnossnn, of the city, county, and State ofNew York, have invented a new and useful Improvement in Pin-Drills; andI hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanyingdrawings, forming a part of this specication, in which- Figure lis anend view of a drill constructed according to my improvement, as seenfrom below 5 and Fig. 2 is a vertical section of the same.

Similar letters of reference represent corresponding parts in bothigures.

The object of this invention is to provide for the drilling` of holes oflarge size into iron, stone, or other material, without the necessity ofrst drilling` a smaller one, as is necessary for the guidance of the xedcenter-pin of an ordinary pin-drill.

The invention consists in furnishing the drill with a central pin,composed of a separate piece fitted into the stoel; or body of thedrill, with a screw-thread or spiral guide, in such manner that whilethe said pin serves to center the drill at the commencement of itsoperations by working on a bearing produced in` the surface ofthematerial to be drilled, by a center-punch or other means, it recedeswithin K the drill relatively to the cutting-edges as the drillingproceeds, and so retains its proper bearing on the material andcontinues to eenter the drill.

To enable others to understand the construction and operation of myinvention, I will proceed to describe it with reference to the drawings.

Ais the stock or body of the drill, provided with cutting-points, orfitted with cutters B B B, substantially like those of the pin-drill incommon use, or of any suitable construction.

G is the centerguide pin, which may be screwed into the stock or body inthe usual manner of screw and nut, and with single,

double, or treble, or any number of threads; or it may have but onethread working into the stock, as a helical feather may be fast to thestock; or, instead of a feather, a pin may replace it and run in thegroove forming the female part of the screw, whether the one or theother is in the guide-pin or the stock of the drill.

The outer extremity of the guide-pin may have a smooth, plain conical.point, as represented; or faces may be ground upon the conical end ofthe pin, to form pyrainidal reamers or countersinlrs; or the cone may befluted for that purpose, if it is desirable to obtain more frictionalhold upon the material to be drilled than could be obtained with asmooth cone, in which case a less pitch of the screw will be desirable,according to circumstances.

To use this improvement, the material to be drilled should first receivean indentation, by means of a center-punch or otherwise, in the centerof where the hole is to be drilled, for the reception of the point ofthe guide-pin C. The center-guide pin C must then be turned backward,and out ofthe stock only so far as will project its cone-point a littlebeyond the points of the cutters B. The material may then be applied sothat the point of the center-pin will come in contact with and enterinto the indentation made therein by the center-punch or otherwise, asabove described, and the drill may either be fed down to the material orthe material fed up to the drill. In either case the center-point C willcease to turn with the same velocity of the stock, but will be somewhatretarded by friction of the point against the material, and by whichmeans, though still having, in some degree, the rotary motion of thestock, it is not progressive in its movement, as are the cutters, and,though occupying the same position relative to the material, yet recedesrelatively to the cutting-points B, by means of the forward feed-motionof the drilling operation, and is by degrees screwed back into the stockin a degree proportionate to the feeding process of the drillingperformance, retaining all the while its point within the centerindentation in the material, and guiding the cutters thereb yB y meansof this improvement holes of large size may be drilled more truly thanwith the ordinary pin-drill, which requires the preparatory drilling ofguide-holes for the center-guide pin, besides saving the time and laborin the drilling of such guide-holes.

That is here claimed as my invention, and desired to be secured byLetters Patent, is

The combination of the hub A and its bits B with the spirally-guidedcenter-pin, all constructed and arranged substantially as set forth.

THOS. PROSSER. Witnesses:

A. LE CLERC, A. KINNIER.

